﻿l8 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  Crystal 
  outlines 
  are 
  sometimes 
  distinct. 
  Professor 
  Kemp 
  has 
  noted 
  

   a 
  similar 
  pyroxene 
  in 
  the 
  syenite 
  of 
  the 
  Elizabethtown-Port 
  Henry 
  

   quadrangles 
  and 
  he 
  suggests 
  the 
  presence 
  of 
  the 
  jadeite 
  molecule 
  

   in 
  its 
  composition. 
  Garnets 
  seldom 
  occur 
  in 
  this 
  syenite. 
  

  

  The 
  most 
  basic 
  rock 
  of 
  all 
  is 
  shown 
  by 
  no. 
  I 
  of 
  the 
  table. 
  This 
  

   rock 
  makes 
  up 
  the 
  Bull 
  Rock 
  mountain 
  mass. 
  It 
  is 
  unusually 
  high 
  

   in 
  plagioclase, 
  pyroxene, 
  and 
  biotite 
  and 
  low 
  in 
  quartz, 
  and 
  is 
  nearer 
  

   the 
  gabbro 
  in 
  appearance 
  and 
  composition 
  than 
  any 
  other 
  rock 
  of 
  

   the 
  whole 
  region. 
  It 
  is 
  fine 
  to 
  medium 
  grained 
  and 
  of 
  rather 
  a 
  

   bluish 
  gray 
  than 
  greenish 
  gray 
  color 
  when 
  fresh. 
  

  

  Numbers 
  2 
  and 
  3 
  of 
  the 
  table 
  are 
  from 
  the 
  mountain 
  2 
  miles 
  

   south-southeast 
  of 
  Riverside, 
  and 
  from 
  along 
  the 
  road 
  1 
  mile 
  west- 
  

   southwest 
  of 
  Daggett 
  pond 
  respectively. 
  In 
  the 
  field 
  it 
  is 
  generally 
  

   impossible 
  to 
  distinguish 
  this 
  pyroxene 
  syenite 
  from 
  much 
  of 
  the 
  

   granitic 
  hornblende 
  syenite 
  and 
  this, 
  together 
  with 
  the 
  fact 
  that 
  the 
  

   two 
  rocks 
  grade 
  perfectly 
  into 
  each 
  other, 
  renders 
  separate 
  map- 
  

   ping 
  practically 
  impossible. 
  The 
  pyroxene 
  syenite, 
  however, 
  is 
  

   certainly 
  less 
  common 
  than 
  the 
  hornblende 
  syenite. 
  

  

  Granitic 
  hornblende 
  syenite. 
  The 
  range 
  in 
  mineral 
  composition 
  

   of 
  this 
  rock 
  is 
  shown 
  by 
  the 
  selected 
  examples 
  given 
  in 
  table 
  1. 
  

   Microperthite 
  and 
  orthoclase 
  are 
  always 
  present 
  though 
  in 
  very 
  

   variable 
  amounts, 
  while 
  the 
  quartz 
  and 
  hornblende 
  contents 
  are 
  

   high 
  and 
  biotite 
  is 
  scarcely 
  represented. 
  In 
  addition 
  to 
  the 
  minerals 
  

   shown 
  in 
  the 
  table 
  a 
  few 
  scattering 
  garnets 
  sometimes 
  occur. 
  No. 
  

   7, 
  with 
  its 
  almost 
  total 
  lack 
  of 
  hornblende, 
  is 
  an 
  unusual 
  type. 
  

   The 
  gneissic 
  structure 
  is 
  usually 
  well 
  developed 
  though 
  at 
  times 
  

   it 
  becomes 
  very 
  faint. 
  This 
  granitic 
  syenite 
  on 
  the 
  one 
  hand 
  grades 
  

   perfectly 
  into 
  the 
  pyroxene 
  syenite 
  and 
  on 
  the 
  other 
  into 
  the 
  gran- 
  

   ites 
  below 
  described. 
  Arbitrarily, 
  when 
  the 
  quartz 
  content 
  passes 
  

   beyond 
  25 
  per 
  cent, 
  the 
  rock 
  is 
  classed 
  as 
  granite 
  and, 
  as 
  nearly 
  

   as 
  possible, 
  the 
  rocks 
  have 
  been 
  separately 
  mapped 
  on 
  this 
  basis. 
  

   The 
  very 
  common 
  presence 
  of 
  biotite 
  in 
  the 
  granite 
  has 
  also 
  been 
  

   a 
  help 
  in 
  mapping. 
  

  

  Numbers 
  4, 
  5, 
  6, 
  and 
  7 
  are 
  respectively 
  from 
  Potter 
  mountain, 
  

   i 
  l 
  / 
  2 
  miles 
  east 
  of 
  Pottersville, 
  one-third 
  of 
  a 
  mile 
  north 
  of 
  the 
  north 
  

   end 
  of 
  Loon 
  lake, 
  and 
  the 
  summit 
  of 
  Little 
  mountain. 
  

  

  GRANITE 
  

  

  As 
  already 
  stated, 
  the 
  granitic 
  syenite 
  passes 
  through 
  perfect 
  

   gradations 
  into 
  the 
  granite 
  and 
  these 
  rocks 
  are 
  very 
  clearly 
  only 
  

   different 
  phases 
  of 
  the 
  same 
  great 
  intrusive 
  body. 
  The 
  rock 
  is 
  

   rather 
  arbitrarily 
  called 
  granite 
  when 
  it 
  contains 
  more 
  than 
  25 
  

  

  